Fluid handling apparatus



Oct. 6, 1964 J. DURSTESERGER 3,151,566

FLUID HANDLING APPARATUS Filed April 30, 1963 gscfi DuasTseese/z UnitedStates Patent 3,151,566 FLUID HANTJLENQ APPARATUS Josef Durstherger, Lmz(Danube), Austria, assiguor t0 Konrad Rosenbauer 3.6., Linz, Austria, acompany of Austria Filed Apr. 39, 1963, Sar. No. 276,841 1% Claims.(ill. 103-413) Because centrifugal pumps are not self-priming, an airpump is required, which operates until the centrifugal pump has suckedliquid; then the air pump can be disconnected. To facilitate theoperation, it is already known to provide a control device whichautomatically energizes and deenergizes the air pump in dependence onthe liquid pressure in the centrifugal pump. This control devicecomprises in most cases a spring-loaded control member, which consistsof a piston or diaphragm and to which liquid under pressure is suppliedfrom the centrifugal pump. When the centrifugal pump has been filledwith water and the pressure in the centrifugal pump rises above acertain minimum value, the piston or diaphragm is moved against theforce of the spring to deenergize the air pump. When the suction columnbreaks down during the operation of the centrifugal pump, the liquidpressure will drop and the movement of the piston or diaphragm in theopposite direction under the action of the spring will cause the airpump to be re-energized. In pumps which must often handle impure Water,such as fire pumps, this control device tends to become soiled after ashort time and must often be cleaned or may sometimes become entirelyuseless. Most dangerous are hard and granular impurities, such as sand,which are not emulsified in the water and tend to settle.

It is an object of the invention to provide a centrifugal pump whicheven when handling highly contaminated water does not result in soilingof the automatic control device or in a disturbance of its operation sothat the pump has an increased reliability and for this reason isparticularly suitable as a fire pump.

The invention is based on a centrifugal pump comprising an air pumpwhich is automatically energizable and deenergizable by means of acontrol device in dependence on the liquid pressure in the centrifugalpump. The invention resides essentially in that the tap for the liquidunder pressure for actuating the control device is disposed close to theimpeller shaft of the centrifugal pump. Because the particularlyundesirable, hard and granular impurities have a higher specific gravitythan water, they will accumulate near the outer periphery of the path ofthe water gyrating in the pump whereas their occurrence decreasesprogressively toward the impeller shaft. According to the invention, thewater under pressure is taken from a point near the impeller shaft,i.e., from a region when no grains of sand or the like, which mightcause a disturbance of the function of the control device, are to heexpected, and the control device is fed only with water which has beenfreed from such impurities to a considerable extent.

A further improvement is achieved in that the tap is disposed in a spacewhich communicates with the remaining space of the pump only through anarrow gap defined by a wall and an annular rib on the rear face of theimpeller. To avoid a settling even of fine particles of mud in thecontrol device and to prevent the same from freezing in the cold season,the control device has gaps or the like which are open to ermit of aflow of the liquid underpressure through them when the air pump isdeenergized; these gaps are somewhat wider than the gap between the tapspace and the remaining space of the centrifugal pump. This results in acontinuous, slight flow through the control device whereby any mudparticles passed through the gap beteen the pump chambers are washed outand the danger of freezing is greatly reduced.

On the rear side of the impeller there is not the full pressure of thepump but only the pressure transmitted through the gap; this pressure isgreatly reduced if the impeller has also the usual thrust balancingbores. Because it is desired to deenergize the air pump immediately whenthe centrifugal pump has been filled with water and because the controldevice should not be too sensitive, the tap in a centrifugal pumpcomprising two or more stages is preferably disposed in a pump spaceassociated with a higher pump stage so that a sufiiciently high liquidpressure will be available for actuating the control device.

The drawing is a diagrammatical axial sectional view showing anillustrative embodiment of the invention.

The two impellers 3 of a two-stage centrifugal fire pump are mounted ona shaft 2 in the housing 1. The suction inlet and the discharge outletof the pump are indicated 4 and 5, respectively. An air pump 19 drivenby an electric motor 20 communicates through conduits 6, 7 with thesuction inlet 4 of the centrifugal pump. The conduits 6, 7 are connectedby a valve 8 which is actuated by a spring-loaded diaphragm 9 mounted inthe valve casing. Liquid under pressure is supplied from the centrifugalpump through a conduit 10 to the diaphragm 9. The liquid is withdrawnthrough a tap 11 close to the impeller shaft 2 from a chamber 12 in thehousing which communicates with the remaining pump cavity only through anarrow gap 14 between an axial end wall of the housing 1 and an annularrib 13 on the rear face of the impeller in the second pump stage.

When the valve 8 is in the closed position shown in the drawing, thediaphragm 9 is lifted against the force of a spring 18. The movablecontact of a switch 15 is attached to the diaphragm. The switch controlsthe motor 26 and is open. The conduits 6, 7 are separated by the movablevalve member 16 which is also attached to the diaphragm 9. The stem ofthe valve member 16 passes freely through a bore 17, which is wider thanthe gap 14 and permits continuous limited flow of water through theconduit 1% and the valve casing into the conduit 7 and back to thesuction inlet l. When there is no pressure in the centrifugal pump orwhen the pressure drops below a certain value, the diaphragm 9 isdepressed by the action of its spring 18 so that the switch 15 is closedand the air pump 19 is started; at the time, the valve member 16 islifted from its seat so that the conduits 6, 7 are connected. During theoperation of the air pump 19, the diaphragm 9 is sufficiently lowered toclose the bore 17 between the orifices of the conduits 7 and 10.

What I claim is:

l. Fluid handling apparatus comprising, in combina tion:

(a) a centrifugal pump including (1) a housing defining a cavitytherein, and

adapted to hold a liquid;

(2) an impeller shaft rotatably mounted in said cavity, said shafthaving an axis, and

(3) an impeller mounted on said shaft in said cavity,

(4-) said housing being formed with a discharge outlet remote from saidaxis, with a suction inlet, and with a tap therethrough adjacent said axs and remote from said inlet;

(b) an air pump communicating with said cavity; and

(0) control means connected to said tap for receiving fluid therethroughfrom said cavity,

(1) said control means being responsive to the pressure of the receivedfluid for operating said air pump.

2. Apparatus as set forth in claim 1, wherein said impellertdivides saidcavity into two portions, one of 7 said portions directly communicatingwith said discharge outlet and with said suction inlet, the otherportion directly' communicating with said tap, said two portionscommunicating with each other through a gap circumferential about saidaxis, said one portion extending radially outward from said gap, andsaid other portion extending radially inward'from said gap.

3. Apparatus as set forth in claim 2, wherein said other cavity portionis axially defined between respective wall portions of said impeller andof said housing, said apparatusfurther comprising an annular rib on oneof said wall portions about said axis, said rib axially extending fromsaid one wall portion toward the other-wall portion and defining saidgap therewith.

4. Apparatus as set forth in claim 2, further comprising a conduitconnecting said air pump with a portion of said cavityspaced from saidtap.

, 5. Apparatus as set forth in claim 2, wherein said control meansinclude a valve interposed between said air pump and said cavity, andpressure-responsive actuator means for operating said valve in responseto the pressure of said received fluid.

6. Apparatus as set forth in claim 2,'wherein said air pumpisrelectrically operated, and said control means include a switch incircuit with said air pump, and

actuator means for operating said switch in response to the pressure ofsaid received fluid.

7. Apparatus as set forth in claim 2, :wherein said air pump iselectrically operated,ran d said control means include a valveinterposed between said air pump and said cavity, a switch in circuitwith said air pump, and actuator means for operating said valve and saidswitch 7 in response to the pressure of said received fluid.

8. An apparatus as set forthrin claim 2, wherein said control meansinclude a casing formed with a bore therein, a first conduit connectinga first portion of said bore to said cavity, a second conduit connectinga second portion of said bore to said air pump, and a third conduitconnecting a third portion of said bore to said tap, first valve meansmovable in said bore toward and away from a closing position in whichsaid first valve ,means separates said second bore portion from saidfirst and third portions, and actuator means responsive to the pressureof the fluid received in said third portion for operating said valvemeans.

9. An apparatus as set forth in claim 8, wherein said first and secondvalve means are operatively connected for joint movement of one valvemeans toward said closing portion thereof when the other valve'meansmoves away from the closing position of said other valve meansp 10. Anapparatus as set forth in claim 9, wherein said air pump is electricallyoperated, and said control means include switch means in circuit withsaid air pump and operable for energizing and deenergizing said airpump, said switch means being connected to said actuator means foroperation thereby in response to said pressure of' the received fluid.

References Cited in the file of this patent UNITED STATES PATENTS1,573,931 Goyne Feb. 23, 1926 1,995,812 Noble Mar. 26, 1935 FOREIGNPATENTS 319,176 Germany Mar '1, 1920 924,068 Germany Feb. 24, 1955 r332,465 Great Britain July 24, 1930 804,265 Great Britain Nov. 12, 1958

1. FLUID HANDLING APPARATUS COMPRISING, IN COMBINATION: (A) ACENTRIFUGAL PUMP INCLUDING (1) A HOUSING DEFINING A CAVITY THEREIN, ANDADAPTED TO HOLD A LIQUID; (2) AN IMPELLER SHAFT ROTATABLY MOUNTED INSAID CAVITY, SAID SHAFT HAVING AN AXIS, AND (3) AN IMPELLER MOUNTED ONSAID SHAFT IN SAID CAVITY, (4) SAID HOUSING BEING FORMED WITH ADISCHARGE OUTLET REMOTE FROM SAID AXIS, WITH A SUCTION INLET, AND WITH ATAP THERETHROUGH ADJACENT SAID AXIS AND REMOTE FROM SAID INLET; (B) ANAIR PUMP COMMUNICATING WITH SAID CAVITY; AND (C) CONTROL MEANS CONNECTEDTO SAID TAP FOR RECEIVING FLUID THERETHROUGH FROM SAID CAVITY, (1) SAIDCONTROL MEANS BEING RESPONSIVE TO THE PRESSURE OF THE RECEIVED FLUID FOROPERATING SAID AIR PUMP.